Schaefer, Richard T, author
McGraw-Hill, Higher Education, 2009
Buku Teks
Schaefer, Richard T, author
New York, 2003
Buku Teks
Schaefer, Richard T, author
McGraw-Hill, 1995
Buku Teks
McGraw-Hill, 2003
Buku Teks
Schrag, Clarence C., author
Harper & Row, 1963
Buku Teks